[Myka]

Your tank is too small for a sand sifting starfish same with conchs. The sandsifting starfish are difficult to keep even in quite large aquariums. You can try larger snails like Astraea or Trochus for cleaning the rocks and glass. I think you're out of luck for a sand cleaner of any sort in a tank that small with a dwarf lion. You can always use a gravel cleaner to clean the top 1/2" of sand. Just use your thumb on the end of the siphon to pause it every once in awhile to let the sand fall back down.

For the ammonia, I woud suggest the use of Prime. If you haven't done a water change since adding the fish I would suggest you do a 25% change.